The U.S. government has a specialized plane loaded with advanced sensors that officials brag is always ready to deploy within an hour of any kind of chemical disaster. But the plane didn’t fly over eastern Ohio until four days after the disastrous Norfolk Southern derailment there last year.

A whistleblower told The Associated Press that the Environmental Protection Agency’s ASPECT plane could have provided crucial data about the chemicals spewing into the air around East Palestine as the wreckage burned and forced people from their homes.

The man who wrote the software and helped interpret the data from the advanced radiological and infrared sensors on the plane said it also could have helped officials realize it wasn’t necessary to blow open five tank cars and burn the vinyl chloride inside because the plane’s sensors could have detected the cars’ temperatures more accurately than the responders on the ground who were having trouble safely getting close enough to check.